Single use laryngoscope

ABSTRACT

A laryngoscope ( 10 ) to assist tracheal intubation on a patient, comprising a body having a handle ( 14 ), and a laryngoscope blade ( 12 ) extending from the handle ( 14 ); a lighting system ( 21 ) including a light source integrated in the laryngoscope body and arranged in use to be activated to adopt an operational mode to provide illumination to the patient&#39;s throat; control means operative to allow only a single occurrence of the lighting system in the operational mode; and wherein once activated in the operational mode, the lighting system provides illumination for only a limited time.

This application claims priority under 35 U.S.C. §371 to InternationalApplication PCT/AU2004/000159, published as WO2004/071285 A1, the entiredisclosure of which application is hereby incorporated herein byreference in its entirety, and claims foreign priority benefits under 35U.S.C. §365(b) to Australian Patent Application Serial No. 2003100092,filed Feb. 11, 2003, and to Australian Patent Application Serial No.2003902127, filed May 5, 2003, the entire disclosures of whichapplications are hereby incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The invention concerns a laryngoscope for use in laryngoscopy includingtracheal intubation in a patient. The laryngoscope is intended for asingle use after which it is to be discarded.

BACKGROUND ART

Laryngoscopes are currently used to assist tracheal intubation on apatient, for example, following induction of general anaesthesia and inadvanced cardiopulmonary resuscitation.

Traditional laryngoscopes, including the battery casing and lightsource, are difficult to sterilise. Some blades with light fittingssimply cannot be autoclaved. Some microbes are not destroyed bysterilisation posing a risk of cross infection between patients whenreusing a laryngoscope. The sterilisation of a laryngoscope blade alsoreduces its functional life.

Disposable laryngoscope blades designed for single use have beenmanufactured to address these problems. These laryngoscopes, such as theWelch Allyn Expendable Layngoscopes (Model 69090), utilise a reusablepen light torch as a light source that inserts into the blade handle.After the laryngoscope has been used, the light source is removed sothat it can be reused, and the blade and handle are discarded.

DISCLOSURE OF THE INVENTION

In a first aspect the present invention provides a laryngoscope toassist tracheal intubation on a patient, comprising a body having ahandle, and a laryngoscope blade extending from the handle; a lightingsystem including a light source integrated in the laryngoscope body andarranged in use to be activated to adopt an operational mode to provideillumination to the patient's throat; control means operative to allowonly a single occurrence of the lighting system in the operational mode;and wherein once activated in the operational mode, the lighting systemprovides illumination for only a limited time.

An advantage of this aspect of the invention is that the lightingsystem, which is integrated in the laryngoscope body, is designed onlyfor a single use. As such, the lighting system operates as a safetyfeature as once the lighting system has expired, the laryngoscope isrendered useless and therefore the chances of it being reused aresubstantially reduced. Furthermore, by being unable to re-activate thelighting system in a used laryngoscope provides positive evidence thatthe laryngoscope has been used and therefore should be disposed of.

The period in which the light source remains active is preferablypreselected by the manufacturer and is long enough to adequately coverthe length of the surgical procedure in which the laryngoscope is used.It is desirable that the period of activation of the lighting system isnot excessive as it may encourage secondary use of the laryngoscope andalso lead to an unnecessary increase in the cost of manufacture of theinstrument. Typically the length of period is in the order of one or afew hours.

The lighting system may provide illumination in the operational mode fora period in the order of one to three hours.

The control means may include an activation device that is operative toactivate the lighting system to adopt the operational mode but isprevented from subsequently de-activating the lighting system.

The activation device may be in the form of an insulating tab whichprovides a break in the lighting system circuit, the tab includes an endwhich projects outside the laryngoscope body so that it can be manuallyremoved and wherein once removed, the lighting system circuit isestablished thereby causing activation of the lighting system.Advantages of the insulating tab is that it provides an inexpensive oneway switch and also it provides an indicator to a user as to whether thelaryngoscope has been used. However, it needs to be appreciated thatother types of one way switches may be used as will be appreciated bythose skilled in the art.

The activation device may be in the form of a switch that incorporates apart that is movable on the laryngoscope body from a first position to asecond position to activate the lighting system to adopt the operationalmode, but is inhibited from movement from the second position to thefirst position.

The part may be formed as an end portion of the laryngoscope body.

The period of activation of the lighting system in the operational modemay be determined by the life of a power supply. The power supply, whichtypically is one or more batteries, is chosen so that its lifespan iscommensurate with the desired length of activation of the lightingsystem.

The control means may include a limiting device operative to establishthe length of period of illumination of the lighting system in theoperational mode.

A power supply may be removable from the laryngoscope body.

The laryngoscope body may include a cover that allows access to thepower supply, and wherein removal of the cover results in at leastpartial destruction of the body.

The cover may be arranged to be snap fitted onto a portion of thelaryngoscope body.

The cover may be the movable part of the activation device.

The lighting system may be operative to adopt a test mode to allow fortesting of the lighting system. After operation in the test mode it isstill possible to operate the laryngoscope in the operational mode.However, it is only possible to activate the laryngoscope in theoperational mode once. The test mode may be limited to a period of timethat is too short to allow intubation of a patient.

When in the test mode, the light source may be illuminated.

The period the light source is able to remain illuminated in the testmode may be substantially shorter than in the operational mode.

The laryngoscope may further comprise an activating device that isoperative to activate the lighting system to adopt the test mode.

The activation device may be operative to activate the lighting systemto adopt both the test mode and the operational mode.

The lighting system may be operative to automatically change from thetest mode to the operational mode after the lighting system has been inthe test mode for a predetermined period.

The limiting device may control the period of illumination of the lightsource in the test mode and operational mode, and wherein when in thetest mode, the period of illumination may be interrupted and recommencedat a later time, whereas in the operational mode, the limiting deviceprevents interruption of the illumination period thereby limiting thelighting system to a single occurrence in the operational mode.

The limiting device may be in the form of an electronic timer connectedto the lighting system circuit.

The lighting system may further comprise a power supply that islocatable within the laryngoscope body.

The power supply may be locatable in the handle of the laryngoscope.

The power supply may be locatable in the blade of the laryngoscope.

The laryngoscope blade may incorporate a cavity in which the entirelighting system is housed, and the body may further include a coverarranged to be locked over the blade cavity so as to prevent access tothe lighting system. Including the entire lighting system within thelaryngoscope blade minimises the number of components used in thelaryngoscope body. Further, the design of the handle can be dictatedpurely by functional aspects rather than needing to provide adequatespace to incorporate components of the lighting system as in previouslaryngoscope designs.

Various types of light sources may be incorporated within the lightingsystem. For example, the light source may be a light emitting diode(LED), a halogen bulb, a krypton bulb or a xenon bulb. In a preferredform, the light source is located in the laryngoscope blade. However, inanother form the light source may be remote from the blade and a lightguide may be provided to direct the emitted light to an outlet in theblade.

The angle between the handle and the blade may be approximately 75degrees so that it is ergonomically easy to use.

At the end of the handle, the side closest to the blade may extendslightly toward the blade to form a slight hook shape. This hookextension enables easier handling of the laryngoscope.

It is an advantage of the invention that after the light system ceasesto be active, the laryngoscope does not have the required functionalityto be properly reused on a patient. As a result, the risk of crosscontamination between patients through the reuse of laryngoscopes isgreatly reduced. This disposable laryngoscope is a low cost alternativeto traditional laryngoscopes, as the construction costs are lower andassociated costs of sterilisation are removed. In this way, a clean andreliable laryngoscope is always ready for instant use.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described withreference to the accompanying drawings. It is to be appreciated that theparticularity of the drawings and the related description does notsupersede the preceding broad description of the invention.

In the drawings:

FIG. 1 is a perspective view of a first embodiment of a laryngoscopeaccording to the invention;

FIG. 2 is a side view of the laryngoscope of FIG. 1;

FIG. 3 is a further perspective view of the laryngoscope of FIG. 1;

FIG. 4 is an exploded view of the laryngoscope of FIG. 1;

FIG. 5 is a perspective view of a lighting system which is housed withinthe laryngoscope of FIG. 1;

FIG. 6 is a plan view of the system of FIG. 5;

FIG. 7 is an elevation view of an alternative lighting system;

FIG. 8 is a perspective view of the body part of an alternativeembodiment of a laryngoscope according to the invention;

FIG. 9 is a perspective view of an end cap for use with the body part ofFIG. 8;

FIG. 10 is a perspective view of a snap on cover for use with the bodypart of FIG. 8;

FIGS. 11 to 13 are views of a populated circuit board for use with thebody part of FIG. 8;

FIG. 14 is a circuit diagram of the populated circuit board of FIGS. 11to 13;

FIG. 15 is a cross section view of yet another embodiment of alaryngoscope according to the invention in the disassembled “OFF” state;and

FIG. 16 is a cross section view of the laryngoscope of FIG. 15 in theassembled “ON” state.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, a single use disposable laryngoscope 10 has a blade12 and a handle 14 attached to one end of the blade 12. The body oflaryngoscope 10 is a one-piece construction made from a hard plastic,that is strong enough to lift 15 kg and smooth enough to glide easilyover the surface of the tongue.

The angle between the blade 12 and the handle 14 is 75 degrees so thatit is ergonomically easy to use. This angle may be varied within aboutplus or minus 15 degrees. The handle 14 is approximately 12 centimetersin length.

The end of the handle 14 is shaped for easier handling. At the end ofthe handle, the side closest to the blade 16 extends slightly toward theblade 12, to form a slight hook shape. This hook extension 16 acts as anudge against the index finger of a user gripping the handle 14 whenlifting during laryngoscopy.

As shown in FIG. 3, the blade 12 has a curvature similar to theMacintosh blade and has a ‘Z’ shaped cross section.

Referring to FIG. 4, the laryngoscope 10 includes a cavity 19 which isarranged to receive a lighting system 21 disclosed in more detail below.A snap on cover 20 locates over the cavity, and once fitted to blade 12,lugs 22 prevent subsequent removal of snap on cover 20.

Referring to FIGS. 5 and 6, the lighting system 21 incorporates apopulated circuit board 24 that is dimensioned to be fitted into bladecavity 19 and be retained by the snap on cover 20. The lighting system21 includes an LED 18, a current limiting resistor 26, and three 3Vbatteries 30. The connection to one of the batteries is interrupted byan activating insulating tab 32 which forms a one way switch for thesystem 21 and which forms part of a control arrangement for thelaryngoscope. Pulling out tab 32 completes the circuit and puts thelaryngoscope into the operational mode causing the LED 18 to beilluminated. The control means further includes a time limiting devicein the form of electronic timer 28 which operates to shut off power toLED 18 after a predetermined time such as one hour or a few hours. Afterpower has been shut off the electronic timer 28 prevents it from beingrestored.

Electronic timer 28 may take any one of three forms as follows:

Timer circuit A-A programmable, time count micro controller and a relayare employed. The set operational period, one hour, is counted from themoment the light source is activated. The time tolerance is programmableto plus or minus 2 or 3 minutes, and a warning off/on flash isprogrammable to activate two minutes before the power is cut off. Therelay can operate at 3 volts and has a fairly low consumption ofcurrent, around 600 mAmp.

Timer circuit B-A programmable micro controller and transistors areemployed. This requires 1 resistor and 3 transistors to replace therelay of Timer circuit A. All other functions are identical. The currentrequirement would be roughly 3.6 volts and 650 mAmp. In either of timercircuit version A or B, once the time count micro controller has beenactivated, it cannot be activated again. This means that replacement ofbatteries does not allow the light source to be activated againfollowing a single operational use.

Timer circuit C-A silicon-based microchip is employed and is surfacemounted to the printed circuit board. The microchip has a number ofintegrated functions as follows:

-   -   the interruption of power to the laryngoscope's lamp after 60        minutes of operation:    -   initiation of a series of rapid flashes of the lamp 5 minutes        before the pre-set time has elapsed    -   the tolerance for the interruption of the power supply to plus        or minus 2 minutes    -   the low voltage cut-out of power to the lamp should the voltage        produced by the battery fall to between 2.3 to 2.2 volts    -   The microchip also includes a retaining memory or an electrical        erasable memory, which ensures that if a new set of batteries is        inserted by error or design into a laryngoscope that has already        been used no power will be delivered to the light source. The        microchip is supported by an external capacitor chip that is        also surface mounted on the printed circuit board.

In all of the above timer circuit arrangements, removal and re-insertionof the batteries does not allow for re-activation of the light source inuse. However, in one embodiment there is provided a test mode. In oneform, an initial test period of 60 seconds is provided during whichremoval of the batteries will allow for subsequent activation uponre-insertion of the batteries. In another form, there may be provided aswitch or the like that allows activation of the test mode. The testmode feature is provided to allow for testing of the laryngoscope beforeuse, or to allow for momentary activation due to brief contact with thebattery terminals at the time of inserting the batteries. The testperiod is limited to a short period of time that is insufficient toallow for intubation of a patient in the test mode.

Referring again to FIG. 4, when the lighting system 21 is fitted intothe blade 12, the LED is mounted within a molded aperture 23 (FIG. 3) inthe blade so as to illuminate light from the blade, and the insulatingtab 32 protrudes from a slot 34 formed at the heel of the laryngoscope.This allows tab 32 to be grasped by a user to pull out to activate theLED.

In an alternative arrangement the electronic timer 28 can be omitted asshown in FIG. 7. The light source will remain illuminated until thebattery is drained of power. Again this can be limited to be a shorttime period of one hour or a few hours.

The laryngoscope 10 can be used to assist tracheal intubation. The lightsystem of the laryngoscope 10 is switched on by removing tab 32. Onceactivated, the light source will remain illuminated for a fixed time.The blade 12 is then loaded with the appropriate endotracheal tube andintubation is performed in the usual manner. Once the light systembecomes deactiveated, and the light source is no longer illuminated, thelaryngoscope 10 is rendered useless and cannot be reused on anotherpatient as the light system can no longer be activated. The entire unitis then disposed of, including the battery and light source.

Referring to FIGS. 8 to 14, an alternative embodiment of a laryngoscope110 according to the invention is illustrated. Like parts to the firstdescribed embodiment are indicated with like reference numerals in therange 100-199. In this embodiment, the power source in the form of twoAA or AAA batteries is mounted inside the handle 114. The laryngoscopeis supplied with the batteries already present.

Control means in the form of end cap 116 fits onto the end of handle 114in either of two positions and operates to activate the light source. Inthe first position lug 117A engages with detent 119A. This is the “OFF”position in which the laryngoscope is supplied and remains so until thetime of use. At the time of use end cap 116 is depressed to the “ON”position to cause lug 117B to engage and lock with detent 119A. Thiscauses the batteries to contact terminals 134, 136 to activate the lightsource.

It is not possible to move end cap 116 back to the “OFF” positionwithout the use of force sufficient to damage either of the lug 117A ordetent 119A. This makes it difficult to re-fit end cap 116 and alsoprovides some evidence that end cap 116 has been removed. This featureprovides for removal of the batteries for separate disposal, and todiscourage attempts to replace the batteries.

The light source used is a xenon globe 118. A polycarbonate cap (notshown) is provided around globe 118 to prevent any glass particles fromescaping in the event of a globe exploding. A lens is moulded in the endof the cap to focus light emitted from globe 118. An air gap may beprovided around globe 118 to slow the rate of heating of the blade 112in the vicinity of globe 118.

Snap on cover 120 includes snap fit lugs 122. These fit through mountingholes 125 in circuit board 124 and engage with receiving holes 123.

Referring to FIGS. 15 and 16, cross sectional views of the handle part214 of yet another alternative embodiment of laryngoscope isillustrated. In this embodiment, the laryngoscope is adapted for supplywithout batteries fitted. For the sake of succinctness, only differencesto the second described embodiment will be explained.

FIG. 15 illustrates the “OFF” position. The end cap 216 and batteries230 are not fitted. Aluminium sleeve 238 lines the inside surface ofhandle 214. Control means in the form of end cap 216 operates toactivate the light source and includes a spigot 240 on which is mountedan aluminium cap 242. Battery terminals 234, 236 (see magnified section)are disposed at the mouth of sleeve 238.

FIG. 16 illustrates the “ON” position. The batteries have been fittedand end cap 216 has been pressed home so that lug 217 engages and lockswith detent 219. Pressing home end cap 216 has caused movement of sleeve238 to press against and elastically deform negative battery terminal234. At the same time, spigot 240 pushes end cap 242 into sleeve 238 topress against batteries 230 to urge the positive end of one of thebatteries against battery terminal 236 and hence complete the circuit toactivate the light source (not shown).

Referring to scrap section AA, it can be seen that spigot 240 isslightly offset with respect to the central axis of sleeve 238. Thisensures good electrical contact between end cap 240 and the insidesurface of sleeve 238.

Again, in this third embodiment, the laryngoscope includes an end capmounted and locked on the end of handle to retain batteries in place. Itis not possible to remove end cap 216 without the use of forcesufficient to damage either of the lug 217 or detent 219. This makes itdifficult to re-fit end cap 216 and also provides some evidence that endcap 216 has been removed. This feature provides for removal of thebatteries for separate disposal, and to discourage attempts to replacethe batteries.

Laryngoscopes according to the invention may be sterilised aftermanufacture and despatched in sterile packaging for a single use.

In the claims which follow and in the preceding summary of theinvention, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprising” is used in aninclusive sense, that is the features specified may be associated withfurther features in various embodiments of the invention.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

1. A laryngoscope to assist tracheal intubation on a patient, comprisinga body having a handle, and a laryngoscope blade extending from thehandle, wherein the blade is permanently affixed to the handle; theblade and the handle being formed from hard plastic; an electriclighting system circuit including a light source integrated in thelaryngoscope body and arranged in use to be activated to adopt anoperational mode to provide illumination to the patient's throat; apower supply; control means operative to allow activation of thelighting system in the operational mode and prevent subsequentdeactivation of the lighting system; and wherein once activated in theoperational mode, the lighting system provides illumination for only alimited time.
 2. The laryngoscope as claimed in claim 1, wherein thelighting system provides illumination in the operational mode for a timein order of one to three hours.
 3. The laryngoscope as claimed in claim1, wherein the control means includes an activation device that isoperative to activate the lighting system to adopt the operational modebut is prevented from subsequently de-activating the lighting system. 4.The laryngoscope as claimed in claim 3, wherein the activation device isin the form of an insulating tab which provides a break in the lightingsystem circuit, the tab includes an end which projects outside thelaryngoscope body so that it can be manually removed and wherein onceremoved, the lighting system circuit is established thereby causingactivation of the lighting system.
 5. The laryngoscope as claimed inclaim 3, wherein the activation device is in the form of a switch thatincorporates a part that is movable on the laryngoscope body from afirst position to a second position to activate the lighting system toadopt the operational mode, but is inhibited from movement from thesecond position to the first position.
 6. The laryngoscope as claimed inclaim 5, wherein the part is formed as an end portion of thelaryngoscope body.
 7. The laryngoscope as claimed in claim 1, whereinthe time for which the lighting system provides illumination in theoperational mode is determined by the life of a power supply.
 8. Thelaryngoscope as claimed in claim 1, wherein the control means includes alimiting device operative to establish the length of period ofillumination of the lighting system in the operational mode.
 9. Thelaryngoscope as claimed in claim 8, wherein the power supply isremovable from the laryngoscope body.
 10. The laryngoscope as claimed inclaim 9, wherein the laryngoscope body includes a cover that allowsaccess to a power supply, and wherein removal of the cover results in atleast partial destruction of the body.
 11. The laryngoscope as claimedin claim 10, wherein the cover is arranged to be snap fitted onto aportion of the laryngoscope body.
 12. The laryngoscope as claimed inclaim 8, wherein the lighting system is operative to adopt a test modeto allow for testing of the lighting system.
 13. The laryngoscope asclaimed in claim 12, wherein when in the test mode, the light source isilluminated.
 14. The laryngoscope as claimed in claim 13, wherein theperiod the light source is able to remain illuminated in the test modeis substantially shorter than in the operational mode.
 15. Thelaryngoscope as claimed in claim 14, further comprising an activatingdevice that is operative to activate the lighting system to adopt thetest mode.
 16. The laryngoscope as claimed in claim 15, wherein theactivation device is operative to activate the lighting system to adoptboth the test mode and the operational mode.
 17. The laryngoscope asclaimed in claim 14, wherein the lighting system is operative toautomatically change from the test mode to the operational mode afterthe lighting system has been in the test mode for a predeterminedperiod.
 18. The laryngoscope as claimed in claim 17, wherein thelimiting device controls the period of illumination of the light sourcein the test mode and operational mode, and wherein in the test mode, theperiod of illumination may be interrupted and recommenced at a latertime, whereas in the operational mode, the limiting device preventsinterruption of the illumination period thereby limiting the lightingsystem to a single occurrence in operational mode.
 19. The laryngoscopeas claimed in claim 8, wherein the limiting device is in the form of anelectronic timer connected to the lighting system circuit.
 20. Thelaryngoscope according to claim 1, wherein the lighting system furthercomprises a power supply that is locatable within the laryngoscope body.21. The laryngoscope according to claim 20, wherein the power supply islocatable in the handle of the laryngoscope.
 22. The laryngoscopeaccording to claim 20, wherein the power supply is locatable in theblade of the laryngoscope.
 23. The laryngoscope according to claim 1,wherein the laryngoscope blade incorporates a cavity in which the entirelighting system is housed, the body further including a cover arrangedto be locked over the blade cavity so as to prevent access to thelighting system.
 24. The laryngoscope as claimed in claim 1, wherein thelight source is any one of a light bulb, a LED, a halogen bulb, akrypton bulb or a xenon bulb.